See more of the story

BEIRUT — The Syrian military dropped leaflets on opposition-held territory in the country's north on Wednesday, urging rebel fighters to surrender as the two sides fought for control of a major highway.

The psychological tactics are part of a relentless regime offensive against rebel forces that have recently acquired shipments of badly needed advanced weaponry from Gulf Arab states. Similar campaigns in the past by the regime to reach out to rebels through leaflets and SMS messages failed to achieve results.

The battle for Idlib province in the north is one of a series of flashpoints as government forces wage a fresh campaign against the rebels on several fronts. Regime forces are in firm control of the city, while dozens of rebel brigades hold rural areas outside.

The battle for the highway leading from Latakia province, a mountainous region along the Mediterranean, into Idlib province is crucial to rebel efforts to retain control of the villages and towns they hold in the area. The regime uses the highway to transport weapons and other supplies from the coastal stronghold to its troops in the north.

"Abandon your weapons and return to your family," read one of the leaflets dropped in Idlib and addressed to foreign fighters.

The leaflets signed by the General Command of the Army and the Armed Forces instruct rebels to approach Syrian government checkpoints slowly while waving the paper in the air as a sign of surrender.

The U.N. estimates that more than 93,000 people have been killed in Syria since the anti-Assad revolt began in March 2011. With so much bloodshed and much of the country still contested, the regime's call Wednesday to surrender was highly unlikely to find any takers on the rebel side, either Syrian or foreign.

Idlib holds strategic value to the rebels because it borders Turkey, which has been a critical source of weapons shipments and other supplies. Latakia province, meanwhile, is predominantly home to members of the president's Alawite sect, an offshoot of Shiite Islam.

In recent months, rebels have accessed more powerful weaponry, including anti-tank missiles and surface-to-air missiles, likely supplied by Qatar and Saudi Arabia.

Last month, President Barack Obama announced the United States would begin providing arms and ammunition to rebels, after Assad's military dealt the rebels serious setbacks and the U.S. said it had evidence the regime used chemical weapons against the opposition. But there is no sign yet of American weapons shipments reaching opposition fighters.

On Wednesday, troops dynamited a highway bridge near the northern city of Jisr al-Shughour, and demolished other parts of the road, according to Fuad al-Deek, an activist based in Idlib province.

Syrian troops fired mortar shells and conducted airstrikes to try to dislodge the rebels, according to the British-based Syrian Observatory for Human Rights, which has a network of activists on the ground.

Al-Deek said the rebels fighting for the Idlib highway were from two Islamic brigades, Suqour al-Sham and Ahrar al-Sham. He said they were struggling to obtain weapons to keep up their fighting, despite the recent influx of arms.

Continuing their fight to try squeeze out regime forces from Idlib, rebels were besieging the provincial capital, causing food shortages and price hikes, said al-Deek and another activist based in the city, Mohammad Kenaan.

They said the siege had continued for the past two weeks, with rebels erecting checkpoints, blocking some roads with large rocks and destroying others, and preventing food and other basic supplies from entering.

"Residents are pleading with the Free Syria Army to loosen their grip, but they are trying to pressure people to leave Idlib," Kanaan said via Skype.

Syria's conflict began in March 2011 with largely peaceful protests against Assad's rule but escalated into a civil war in response to a brutal government crackdown. The conflict has since taken an increasingly sectarian bent, with mostly-Sunni rebels assisted by foreign fighters from across the Muslim world. Assad's forces are bolstered by fighters of the Lebanese Shiite group Hezbollah.

The British-based Observatory also reported fighting in the northern province of Aleppo, in towns on the outskirts of Damascus as well as in the southern province of Daraa.

In the central city of Homs, Syrian troops backed by Hezbollah fighters were encircling the neighborhoods of Khaldiyeh and Bab Houd in the central city of Homs. Rebels have held those districts for the past year.

"The war here is now from building to building. They are trying to take the area a block at a time," said Homs-based activist Tariq Badrakhan via Skype. He added that Syrian forces were "cleaning" the area of rebel fighters by firing mortar shells at buildings.

In Damascus, Syria's state news agency said engineering units dismantled a bomb placed inside a car near the Opera House, a landmark building in the cpaital. It also said a mortar shell landed on the roof of a church in the mainly Christian al-Qassaa district in Damascus, causing material damage.

Hundreds of thousands of Syrian civilians have been internally displaced because of the more than two-year conflict, and the U.N. estimates that another 1.7 million Syrian refugees have fled to neighboring Jordan, Turkey and Lebanon, many of them children.